Man, I've started a brujaha over on some of the UK forums... Some folks over there claim that using a synthetic motor oil in an engine "designed for petroleum-based oil" will negatively affect or even ruin the engine.

However... I'm finding lots of data from AMSOIL and all of the major oil manufacturers (who, I'd think would know the actual skinny) that synthetic oil is actually BENEFICIAL to older engines becasue it's viscosity is more consistant at differing temperatures (high and low) and because it generates less sludge.

I also found this article, written my an AMSOIL employee that talks about synthetic oil:

http://www.whatprice.co.uk/car/synthetic-oil.html

Specifically:
----------------------------

Synthetic motor oils damage seals.

Untrue. It would be foolhardy for lubricant manufacturers to build a product that is incompatible with seals. The composition of seals presents problems that both petroleum oils and synthetics must overcome. Made from elastomers, seals are inherently difficult to standardize.
Ultimately it is the additive mix in oil that counts. Additives to control seal swell, shrinkage and hardening are required, whether it be a synthetic or petroleum product that is being produced.

and...

Synthetic oils are too thin to stay in the engine.

Untrue. In order for a lubricant to be classified in any SAE grade (10W-30, 10W-40, etc.) it has to meet certain guidelines with regard to viscosity ("thickness").
For example, it makes no difference whether it's 10W-40 petroleum or 10W-40 synthetic, at -25 degrees centigrade (-13F) and 100 degrees centigrade (212 degrees F) the oil has to maintain a standardized viscosity or it can't be rated a 10W-40.

--------------------

And yet... Several people are saying that switching off synthetic stopped previous leaks. It doesn't seem to make any sense...

As for me, I'll stop topping off with the Castrol synthetic stuff I bought and I'll stasrt using the Castrol High Mileage until I get my replacement gearshift seal. When I have the oil out of the car to do the swap, I'll replace it with a fresh load of High Mileage - synthetic or not, it has the right additives to recondition the seals and hopefully keep fresh leaks from springing up.

If you have synthetic/petreoleum-based experiences with your classic that you'd care to to share please do so - the more real-world data we can all share in here the better!

 

I don't think imagox would have a problem of losing too much oil in the tranny as classic Mini's oil is shared by the engine and the transmission. As long as you routinely check and top-off when necessary then you should be fine.

that's one thing I like about classic Mini's ---> 1 oil change for both engine and transmission.

 

Matt, well we have the same problem. I also have a slight oil leak. I haven't checked but I suspect its from the rod change area.

btw, you will get different inputs on type of oil to use. Remember that the classic is a different animal. The engine and the transmission uses the same oil thus the tranny gears are subjected to more sludge or what have you. This is not case with conventional cars on the road today. I have been advised to use 20W/50 (EDIT) oil and to stay away from thinner oils. I have no plans to drive it in winter so 20W/50 should be adequate for me.

 

The plot thickens...

http://www.miniresource.com/forums/i...0&#entry404847

Not sure how muich of this applies to Minis (do they have push-rod type or roller-type cams?) but the bottom line in the thread linked here is that modern oil seems to be lacking in ZDDP (an additive present in older oil formulas), to whit:

"For you science buffs: ZDDP is a single polar molecule that is attracted to Iron based metals. The one polar end tends to “Stand” the molecule up on the metal surface that it is bonded to by heat and friction. This forms a sacrificial layer to protect the base metal of the cam and tappet from contacting each other. Only at very high pressures on a flat tappet cam is this necessary because the oil is squeezed/wiped from the surface. This high pressure is also present on the gudgeon pin (wrist pin) in diesel engines, therefore the need for ZDDP in diesel engines.

Second part of the equation is Molybdenum disulfide (Moly). The moly bonds to the zinc adding an additional, very slippery, sacrificial layer to the metal. I found out that too much of the moly will create problems; lack of this material reduces the effectiveness of the ZDDP. The percentage, by weight is from .01 to .02%, not much, but necessary.

Latest conclusions: Running our older, broken in engines on Castrol 20W-50 GTX is ok.
Break in a new engine for 3,000 miles on HD 30 Castrol.
New engines (after break-in) and fairly low mileage engines will do best with the Redline 10W-40 or 10W-30 synthetic."

Nothing in that article re" leaks with syhthetic vs petroleum-based lube, but I found it interesting. Lots of the article above pertains to rebuilt engines on break-in, but they do make some recommendations for Castrol GTX in broken-in engines.

As for the High Mileage formula - I went to Autozone to pick some up (gallon jugs are on sale for $11.88 right now), but when I got there I found that they only carry 20W-50 weight in standard quart size. I bought 2 quarts of High Mileage just to top off with, and when I get my seal kit I'll try to find a gallon of 20W-50 at Walmart or someplace else. Autozone's price is like $3.88 per quart (so abut $24 per case) - can someone please confirm that Walmart or someplace else carries 20W-50 in gallon size there?

On the bright side, the rear pockets can hold 2-3 quart-sized bottles of oil like they were specifically built to do so.

 

I will throw my 2 cents worth in here -- I have been running regular, non-High mileage Castrol GTX 20-50 in my classics year round for a l.o.n.g time and it has worked well. Many moons ago, there was a guy called Crazy Mike that had worked at Seven Ent when they were still in Virginia and he heavily autocrossed a ratty looking but very quick classic Mini with amazing success. He ran M*b*l* One synthetic oil as he wanted to have the "best oil" he could to protect the engine/gearbox. Sometime after he switched to synthetic, the car started to experience differential failure. He asked the manufacturer of that oil if there was a problem using their synthetic oil in the classic Mini. He got a reply that their synthetic oil was fine in the engine, also in the gearbox, but the shear forces generated in the differential (which uses the same oil as engine and gearbox) would break down their synthetic oil and they recommended he not to use it. I actually saw that letter, so this is not heresay, and ever since, I have not considered using synthetic in my classic Minis.

With all the fun involved in removing the roll-pin in the linkage for rod change gearboxes, I am extremely happy that I no longer have a classic with the rod change shifter. Good luck, Matt, and when do you need me to come over to fight the darned thing with you???

Paul

 

we have push-rods.

 

Hehehe... the new seal kit shipped today, so hopefully I'll have it by the end of the week. I was hoping to crawl under the car this weekend - if you're going to be around, I'd love to have some moral (or even better, technical) support, Paul. I'll supply the beverages (your choice) and the grillables if so.

As for Castrol GTX - that's what I'm leaning towards at the moment, and the High Mileage stuff doesn't seem to cost that much more, so I figure why not? I was planning on putting back in whatever oil the previous owner had in there after the seal swap, burt I figure this is a good excuse to just switch everyhing over. Unless he gets back to me and recalls that he used the GTX in the first place - he might have seeing as how he seemed pretty knowlegable about the car and did all his own work. I've sent him an email asking him if he remembers...

Thanks, guys! I'll keep everyone filled in on how it goes. If nothing else, this has taught me MUCH more about oil than I ever dreamed.

 

You might want to think again about the tech support, as the last one of these I had a part in, the @#%*& roll-pin split and was no good. We ended up using a 6-penny nail in its place and just bent it over to keep it in place -- last I heard it was still holding!

 

Hehehe... whatever works, right? I'm just hoping that I have a tool to get the roll pin out - my punches are all tapered (not flat which I hear can make them mushroom) and I suspect that they're way too large.

 

The key thing to remember about Minis is as has been stated before the gearbox and differential share the same oil as the engine unlike most other cars. It was designed in the days of thicker mineral oils like Castrol and Duckhams 20-50s. The engine alone could survive on a thinner synthetic oil (maybe with a few more leaks) but the transmissions life will be severely shortened with the use of such an oil as many have found to their cost.

 

:: Nods ::

That seems to jibe with what I've heard from Paul and others... Lots of people seemed to feel this was so, but very few could explain WHY, and the internet being what it is, well, let's just say that I've learned my lessons about accepting what you're told at face value from strangers.

The more that people weigh in on this, however, seems to confirm that despite what ALL the oil manufacturers say, a petroleum-based oil is the better option for our cars, since the differential is using the same oil supply as the gearbox.
Am I a hopeless geek because I find this fascinating?

 

Its all to do with this:-
"The combined engine/transmission layout places extra demands upon the oil in terms of extreme pressure requirements for gear protection along with ball, roller and needle bearings incorporated into the gearbox."
Millers even make special grade of 20-50 for classic Minis.
Millers Oils
TRANS M 20w50
Formulated for engines from 1960 onwards where engine and transmission share a common lubricant. Ideal for minis and bikes where the clutch runs in engine oil. The additive package protects ball, roller and needle bearings found in the gearbox and provides EP protection levels higher than conventional engine oil and equal to API GL4 for gearboxes.
Trans M 20w50 Data sheet 2113 Mineral, classic engine oil for combined engine and gearbox e.g. mini.

 

Wow... looks good. But abut $40 per gallon, and that's before shipping from the UK - somewhat costly. Do they sell this in the States someplace?

 

Stick to Castrol 20w50, it's even good for your dashpot oil in the carb. Synthetics make a big difference......






in your wallet! especially if it leaks.

 

Synthetics not too good for the trans synchros. Crazy Mike ended up welding the diff to make a Posi, and stuck with motorcycle oil- Yamalube.

Make sure your mini is not leaking from the small hole at the bottome of the flywheel housing as many of them do. This indicates main seal failure and high likelihood of oil contamination of the clutch.

Pick an oil with ZDDP such as Castrol. Otherwise this can happen:



dr dave

 

I've heard this exact same info from a totally different source.

 

Maybe we could just have them ship a barrel of it and use it as community stock?

I guess the old adage holds true. Most cars top off the oil and fill up the petrol when they get to a filling station. Minis top off the petrol and fill up the oil!

 

When I did the London to Brighton run last month, a fellow miniac commented on my chattery gearbox. The first thing he asked was I was using the synthetic oils. I said, "Yes." He then explained to me that was the reason my gearbox was chattering. After that day I stopped using Pensoil 20/50 and most of my leaks have tappered off. Plus the gearbox isn't as chattery on takeover anymore.

What I use now is Halford's Classic mineral oil. It is thicker.

 

I've always been an ardent Castrol GTX 20W50 fan. But since oils are being reformulated w/o ZDDP, I have begun looking for those that still have it. Autozone carries Valvoline VR1 Racing Oil in 20W50 which still includes ZDDP and other anti-wear additives. So, I 've switched over to be safe. Be sure not to buy the "Energy" saving oils as they are w/o ZDDP.

As far as the synthetics leaking more than petroleum...someone explain how two fluids have the same viscosity (20W50) but one is "thinner" than the other????

As far as the roll pin, put it in reverse gear. Use the correct size diameter punch. Don't use a nail, or other piece of junk as you'll only make it more difficult or bugger it up. Spray it liberally with a rust penetrant beforehand.

 

You don't have a diagram or image of where I should look by any chance, do you? I'm pretty sure my leak's coming from the gearchange shaft, but I'll check this as well while I'm under the car. A leak here is only fixable with a full main seal replacement, right? Hopefully I don't have one there...

 

The owner just let me know tha he put in Valvoline non-synthetic 10W-30 in his last change... Looks like a full change is in order.

 

What is that??

 

Those are valve lifters. The wrong oil has caused them to wear & more than likely the camshaft is worn badly too.

 

British cars only ever get one oil leak. But it's neverending!

Actually, when I rebuilt the engine on my MGB, leaks became a thing of the past. It's all in the products used.

 

The lifters(cam followers) are toast because of lack of proper lubricant. ZDDP is added to avoid such contact wear. The cam would definitely be toast, too...